Australian Slang, (noun) A person that is totally lacking in fashion sense, motor skills and/or social skills. Usually a total moron, an extremely unpleasant person or an unwanted guest.
Sometimes: A likeable idiot or Bogan (especially in Queensland)

1. No wonder he can't get a girlfriend, he is such a gronk!
2. Why would you "steal my car for the weekend," you gronk!

A citizen who was born in or lives in the Australian town of Cessnock. They wear cheap plastic thongs, footy shorts and walk around proclaiming about how great there local football team "The Goannas" are.

One who is a bitch, an ass kisser, a muppet.You can slap him around and he wont do shit but then when u walk away he will mumble under his breath or bitch about how he was going to kick your ass to his friends.
Not enough of a man to talk to a women.
Prone to sucking up and talking about themselves alot.
Possibly lacking in testosterone or testicles

Nik: "This guy at the pub today said i was a dirty little faggot and kicked me in the scrote, and i was going to fuck him up , he's lucky i had an itchy ass crack or i would have kicked his ass with my mad wicked kung fool skills! Fuck i'm a mad cunt, I was fully going to hit on his hot girlfriend too, after i kicked his ass , cos i looked at her and she smiled at me, or blinked or something, yeah she wants me man! I'm the sexiest guy alive, i'm so hot i dont need to talk to her she should come and talk to me, i never get laid whoo"
Everyone else: "You Gronk!"